Finishing articles and support members therefor, finishing materials and method of making same



Sept. 22, 1964 H. M KAY, JR, ETAL FINISHING ARTICLES AND SUPPORT MEMBERS THEREFOR, FINISHING MATERIALS AND METHOD OF MAKING SAME 2 Sheets-Sheet 1 Filed March 15, 1961 INVENTORS.

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JO sEPJ-IIIMACIQ QQ P 22, 1954 J. H. M KAY, JR.. ETAL 3,149,442

FINISHING ARTICLES AND SUPPORT MEMBERS THEREFOR, FINISHING MATERIALS AND METHOD OF MAKING SAME Filed March 15, 1961 2 Sheets-Sheet 2 8 0552! J1? MACK A y, (IQ, Maw U. MEIKELLAQ,

INVENTOR-S.

United States Patent FINISHING ARTICLES AND SUPPORT MEM- BERS THEREFOR, FINISHING MATERIALS AND METHOD OF MAKING SAME Joseph H. MacKay, Jr., 22711 MacFarlane Drive, Woodland Hills, Calif., and Melvin J. McKellar, 6707 Kent Land St., Canoga Park, Calif.

Filed Mar. 15, 1961, Ser. No. 96,030 15 Claims. (Cl. 51195) This invention relates generally to the art of finishing and more particularly to abrasive finishing materials, finishing articles constructed from the material, supporting members for use in combination with the finishing articles, and the method of manufacturing the finishing articles.

Prior art finishing articles for the most part, and particularly those which are rotatable and disposable, are constructed of a sheet of finishing material having a fibre backing member thereon with a fibre driving means affixed to the backing member. Although such abrasive finishing articles serve the purposes for which they are intended, experience has shown that several disadvantages are inherent therein, particularly with respect to the fibre driving means.

It has been found that the fibre material normally used in abrasive finishing articles, and particularly that fibre which is used for the driving means is relatively unstable. That is, the physical characteristics of the fibre material appear to change in direct response to the moisture content thereof both during production and thereafter. As a result, it becomes impossible for production personnel to consistently produce finishing articles having the desired quality. For example, if during construction the fibre driving member is warped as a result of its moisture content, it becomes impossible to accurately locate the part with respect to the abrasive finishing material and thus a non-useable product results and it must be rejected. Such warping also introduces many problems which make automated production exceedingly difficult if not impossible. These problems result in a high cost per article.

Furthermore, as a result of the instability in the fibre material, latent fractures hav been discovered in the fibre driving means. Although the exact reason is not fully understood, it is thought that the fractures in the fibre result during the formation of the driving means in the usual manner. It is thought that at the various points of curvature the fibre ends within the material are located and disposed in such a manner that the internal strength of the material is relatively weak. As a result thereof, when the device is placed upon a power tool or when it is applied to a workpiece, the driving means fully fractures and the abrasive finishing article flies off or otherwise becomes useless.

As is well known in the art, it is desirable to rotate finishing articles at very high speeds with complete stability and with the application of large amounts of power thereto While retaining the desired flexibility over a large area. Prior art finishing articles have been exceedingly limited in these areas in that they tend to laterally oscillate at high rotational speeds. Additionally prior art articles tend to tear ofi upon the application of large amounts of power to be subject to inertial fly off thus creating a hazard to personnel. In attempting to correct these problems the desired flexibility has been sacrified.

Accordingly, it is an object of the present invention to provide a finishing article which is more rugged than prior art devices; which will withstand abuse in operation; and which is inexpensive to manufacture.

It is another object of the present invention to provide a finishing article having bonded thereto a drive means which is stable under all operating conditions and which is not subject to breakage orfiy-oif during use.

3,149,442 Patented Sept. 22., 1964 "ice It is another object of the present invention to provide a finishing article having bonded thereto a drive means which may be positively locked to a supporting member and is therefore not subject to lateral movement or vibration during use even at exceedingly high rotational speeds and which withstands the application of exceedingly large amounts of power thereto.

It is another object of the present invention to provide a finishing article which is easily and quickly attached and detached from a supporting member therefor and which has the desired flexibility over a large surface area.

Therefore, in accordance with one aspect of the present invention, there is provided a finishing article which includes a sheet of finishing material having a layer of fabric which has aifixed to at least a portion of one surface thereof a layer of heat plasticizable material. A metallic driving means is permanently bonded to the heat plasticizable material.

More specifically, the metallic driving means preferably is a metal hub having a plurality of openings in a raised portion thereof. Each of the openings is adapted to detachably receive a locking member in the form of a tab in such a manner that when locked in place, a driving surface of the tab and a side of the opening are in a substantiaily interference fit.

It has also been noted in the prior art that holders or supporting members for finishing articles have for the most part been specifically designed only to solve the particular problem of securing the finishing article thereto. Such prior art supporting members generally have a tendency to grow, that is, become larger in radial dimenion as the support member is rotated. Furthermore, it has also been noted that the temperature at the surface of the workpiece increases rapidly during the time that the finishing article is being rotated against it. Prior art supporting members for finishing articles retain the heat thus generated.

Prior art support members have the shaft or spindle thereof constructed as an integral part. Various power tools used in rotating finishing articles have different requirements for attachment of support members to them. Therefore, it becomes necessary to produce a large variety of support members each having different shafts, spindles or other means to accommodate the various power tools.

Accordingly, it is an object of the present invention to provide a support member for a finishing article which is flexible, yet which is firm about the central and surface portions thereof and which thus has limited growth even at high speeds of rotation; which positively and firmly attaches to the finishing article in an easy and quick manner; which may be used with any power tool; and which dissipates heat from the working surface of the finishing article and the work-piece more readily than prior art devices of similar type.

Accordingly, a support member in accordance with the present invention includes a central core having afiixed thereto a locking means for engagement with the finishing article. The central core has a bore which is internally threaded to receive various shafts or spindles for ultimate attachment to a power tool. Disposed around the central core is a relatively rigid, annular member which is preferably constructed of metal. The central core and the annular member are surrounded with a flexible material to form the body of the supporting member. The surface of the support member which contacts the finishing article is provided with an impregnated fabric layer.

Prior art finishing material of the abrasive type has, for the most part, been constructed of fabric or fibre or a combination of the two in laminar form. For many specific applications of finishing materials, it is desirable to bond additional members, such as driving members, backing materials and the like, to the abrasive finishing material. Heretofore it has been necessary to apply a layer of adhesive material to the finishing material and then while the adhesive material is in a wet or fluid state, or at least a tacky state, apply the member to be bonded thereto to the adhesive. Such a procedure obviously necessitates the handling of liquid materials at the moment during which production is being carried out. The inherent disadvantages of such a procedure become obvious to one skilled in the art.

Accordingly, it is an object of the present invention to provide a finishing material having one surface to which other objects such as drive members, backing materials and the like may be readily bonded.

It is another object of the present invention to provide a finishing material which may be stored in a dry state over a long period of time and which thereafter may be have bonded to it other desired objects without the application of adhesives.

A finishing material in accordance with the present invention comprises a sheet of abrasive material which includes as a part thereof at least one layer of fabric which has applied to only one surface thereof a layer of heat plasticizable material. The fabric is preferably penetrated with the plasticizable material which penetrates through the fabric only a predetermined distance, said predetermined distance being less than the thickness of the fabric. The plasticizable material is thus available upon the surface of the finishing material and provides an area or surface to which other materials may be bonded merely by the application of heat thereto.

Further in accordance with the method of the present invention for manufacturing an abrasive finishing article in accordance with the present invention, there is provided a sheet of abrasive material. A layer of fabric is penetrated with a heat plasticizable material through a predetermined portion thereof, the predetermined portion being less than the thickness of the layer of fabric. The layer of fabric is then bonded at the uncoated surface to the sheet of abrasive material. A driving member has applied to at least a portion of one surface thereof a layer of the heat plasticizable material. The driving member and the heat plasticizable material coated surface of the fabric are brought together and heat is applied to thus effect a fusion between the two layers of plasticizable material and thereby to permanently bond the driving member to the finishing article.

Other and additional objects of the present invention will become apparent from a consideration of the following description taken in conjunction with the accompanying drawings which are presented by way of example only and are not intended as a limitation upon the scope of the present invention as defined in the appended claims, and in which:

FIG. 1 is a perspective view of a support member having an abrasive finishing article attached thereto;

FIG. 2 is a cross-sectional view of a finishing material in accordance with the present invention;

FIG. 3 is a cross-sectional view of one step in the preparation of a driving member for a finishing article in accord-ance with the present invention;

FIG. 4 is a top elevational view of a driving member for an abrasive finishing article in accordance with the present invention after it has been produced from the material illustrated in FIG. 3.

FIG. 5 is a cross-sectional view of the structure of the driving member of FIG. 3 taken about the lines 55 thereof;

FIG. 6 is a cross-sectional view of a completed abrasive finishing article in accordance with the present invention;

FIG. 7 is a perspective view of a support member and an abrasive finishing article in accordance with the present invention in disassembled position;

FIG. 8 is a cross-sectional view of the support member illustrated in FIG. 7 taken about the lines 88 thereof and illustrating the finishing article in phantom;

FIG. 9 is a fragmentary top elevational view, partly in cross-section, illustrating the unlocked relationship of the locking members of a support member with respect to the openings in a driving member for an abrasive finishing article in accordance with the present invention;

FIG. 10 is a fragmentary top elevational view similar to FIG. 9 illustrating the locking members in locked position; and

FIG. 11 is a cross-sectional view similar to FIG. 8 illustrating a finishing article being attached to a support member therefor.

Referring now to the drawings, and more particularly to FIG. 1 thereof, there is generally disclosed a finishing apparatus 10 comprising an abrasive finishing article 11 attached to a support member 12 therefor. As is therein illustrated, the finishing article 11 is attached to a locking member, not shown, but which will be more fully described hereinafter, which is an integral part of the support member 12. A spindle or shaft 13 extends from the support member 12 and is adapted to engage a power drive tool (not shown), such as a pneumatic or electric motor, or the like, for purposes of rotating the finishing apparatus 10.

Each of the various elements of the completed structure of the finishing apparatus 10 as illustrated in FIG. 1 Will be described more fully and individually hereinafter.

The Finishing Material Finishing material in accordance with the present invention and from which an abrasive finishing article may be manufactured is illustrated in cross-section in FIG. 2. It should be understood that various illustrations in the drawings are schematic and in some cases have been greatly exaggerated for purposes of clarity and ease of illustration. As is therein shown, a sheet of abrasive material of any type which is presently known to the art, is provided. Preferably, the abrasive finishing material includes a sheet or layer 15 of fabric having abrasive particles 16, such as aluminum oxide, adhered thereto by a layer 17 of adhesive. If such is desired, and as is well known in the art, the layer 17 of adhesive may have a sand-size layer applied thereto to more adequately and firmly bond the aluminum oxide particles 16 to the sheet 15 of fabric.

In the presently preferred embodiment of the finishing material in accordance with the present invention, there is provided a sheet or layer 18 of fibrous material, such as vulcanized fibre or kraft paper. The layer 18 of fibrous material is permanently affixed or secured to the surface of the fabric 15 opposite that surface to which the aluminum oxide particles 16 are adhered. The layer 18 of fibrous material may be secured to the fabric by means of any adhesive which is knovm to the art and which is adaptable for such purposes. For example, a layer 19 of polyvinyl acetate may be utilized for this purpose. A detailed description of the application of the polyvinyl acetate and the adherence of the layer 18 of fibrous material to the fabric 15 will not be described since such is well known in the prior art.

It has been found that the layer 18 is of fibrous material which is laminated within the finishing material in accordance with the present invention, provides that degree of rigidity to the end product which is required for most applications. However, it should be expressly understood that the layer 18 of fibrous material may, in accordance with some design considerations for abrasive finishing material in accordance with the present invention, be dispensed with. Upon thus eliminating the layer 18 of fibrous material from the finishing material as illustrated in FIG. 2, the end product has a higher degree of flexibility which, in some applications, may be desirable.

In accordance with the presently preferred embodiment of the present invention, an additional layer 21 of fabric is adhered to the layer 18 of fibrous material by means of an adhesive 22, such as polyvinyl acetate.

The layer 21 of fabric has a coating 23 of heat plasticizable plastic material affixed thereto. Although any plastic material which meets the requirements of being heat plasticizable may be utilized in accordance with the present invention, it has been found that polyvinyl chloride is an exceptional material for this purpose. Preferably, the coating of polyvinyl chloride is affixed to the layer 21 of fabric by causiu the polyvinyl chloride to penetrate therethrough to a predetermined depth. The predetermined depth of penetration of the polyvinyl chloride is always less than the thickness of the fabric 21 as is illustrated at 24. By thus penetrating the fabric 21 with the polyvinyl chloride to a depth 24 less than its thickness, one surface thereof is maintained in a clean and natural condition. This becomes necessary to provide a clean surface area to which the adhesive will adhere, thus securely and permanently bonding the coated layer 21 of fabric to the finishing material. It has been found that if the polyvinyl chloride, or similar plastic which is heat plasticizable, is permitted to penetrate completely through the layer 21 of fabric so that the underside thereof (as viewed in FIG. 2) has the plastic thereon, adhesives will not adhere thereto.

It should be clearly understood that the coating 23 of polyvinyl chloride is applied to the layer 21 of fabric in any manner which is known to the art or which is desired. After the application of the polyvinyl chloride to the fabric 21, the polyvinyl chloride is cured in the manner well known to the plastics art. As is well known, the polyvinyl chloride is a thermoplastic material so that upon exposure to the proper temperature it cures and forms a coating of solid plastic material upon the layer 21 of fabric.

The thus completed abrasive finishing material as illustrated in FIG. 2 and as above described, may be utilized in the condition as shown or may be subsequently cut into various sizes for future use as individual abrasive finishing articles in accordance with the particular design considerations for the application to which it is to be put.

One such application is the manufacture of an abrasive finishing article in accordance with the present invention.

The Abrasive Finishing Article The abrasive finishing article in accordance with the present invention will now be described, and particularly with reference to the method of manufacturing the same.

First there is provided a section of abrasive finishing material of the type above described and as illustrated in FIG. 2. There is next provided a metallic driving driving member which is to be bonded to the section of abrasive finishing material. The driving member is constructed of a metallic material, such as cold rolled steel. Such material is illustrated in FIG. 3 to which reference is hereby made.

The layer 26 of metal, such as cold rolled steel is first cleaned in any manner desired such as for example by washing with acetone to thereby provide a clean surface to which a layer of plasticizable material may be applied. Thereafter, a primer coat is applied to the thusly cleaned surface of the metal layer 2-6. The primer coat is utilized to cause a coating of heat plasticizable plastic material to adhere to the surface of the metal layer and may be any material capable of accomplishing this result. A coating 27 of heat plasticizable material, for example such as polyvinyl chloride, is then applied to the under surface of the metal layer 26 as is illustrated in FIG. 3. The coating 27 of polyvinyl chloride is then caused to cure in accordance with well known prior art techniques, thus providing a laminar structure of a layer of metal having a coating of polyvinyl chloride adhered to one surface thereof.

After the metal layer 26 is coated with the layer 27 of plastic, as illustrated in FIG. 3, metallic drive members are formed therefrom such as by stamping or the like.

Such a drive member is illustrated in top elevational view in FIG. 4 to which reference is hereby made. As is therein shown, the drive member 31 includes a raised portion 32 having a flange 33 completely surrounding it. Formed in the raised portion 32 are a plurality of openings 34, 34a and 3412 which in the presently preferred embodiment are three in number. It should be specifically noted that each of the openings has a first straight edge 35, 35a, 35b and a second straight edge 36, 36a, 3612 respectively. It should further be noted that the straight edge 36 of the opening 34 is shorter than the straight edge 35 of the opening 34. The construction of the remaining openings is similar. The particular purpose and function of the particular straight edges and their respective sizes will be more fully described here inafter.

Referring now more particularly to FIG. 5 which is a cross-sectional view of the structure of FIG. 4 taken about the lines 5-5 thereof, it can be seen that the drive member 31 in accordance with the present invention includes a layer of metal 25 and a layer of plastic material 27 identical to that which was provided with respect to the discussion above of FIG. 3. It can also be seen that the raised portion 32 and the flange 33 of the drive member 31 take the general configuration of a hat and that specifically the layer 27 of plastic material is present over the entire under-surface of both the flange 33 and the raised portion 32.

Referring now more particularly to FIG. 6 which illustrates a completed finishing article in accordance with the present invention, it can be seen that a section such as a circle of the finishing material as illustrated in FIG. 2 has been cut from a sheet or layer thereof. A drive member in accordance with the discussion with respect to FIGS. 3 through 5 is then brought into contact with the polyvinyl chloride coating 23a in such a manner that the polyvinyl chloride coated under surface of the flange 33 of the drive member 31 is in contact therewith. Heat is applied to the thus contacting members in such a man ner that the polyvinyl chloride plasticizes thus bonding the drive member 31 to the coating 23a of polyvinyl chloride on the abrasive finishing material.

It has been found particularly desirable to apply a very short heat cycle with pressure only locally to the flange area 33 of the drive member 31. In such a manner, the heat plasticizable material immediately adjacent the flange 33 is caused to plasticize and the flange is caused to be depressed into the polyvinyl chloride coating as is illustrated in FIG. 6. Upon the termination of the heat cycle the polyvinyl chloride again sets thus creating a permanent and nondestructive fused bond between the metal drive member 31 and the polyvinyl chloride coating 23a.

The fused bond thus obtained has been found to be surprisingly tenacious. Extreme force has been applied to the edge portions of the metal drive member in an attempt to destroy the bond and it has been found that the metal driving member may bend but that the fused bond is not destroyed. Also exceedingly large amounts of power at very high rotational speeds have been applied to finishing articles of the present invention and it has been found that they perform unexpectedly well under such conditions with no signs of fracture or other breakdown. It has generally been known to use both thermosetting and thermoplastic materials in the abrasives industry As is known a thermosetting material is one which passes from a flowing state to a solid state by the application of heat thereto thus causing the temperature of the material to exceed a predetermined temperature. At room temperature, before setting, the thermosetting ma terial usually is in a solid form. After setting the application of heat will not cause thermosetting material to become fluid or to flow.

A thermoplastic material is a material which becomes fluid as a result of the application of heat thereto. After the application of heat thereto and then a cooling thereof the material is a solid. At room temperature, before the application of heat, the material may be a solid or a liquid. Further application of heat to the material may destroy it or cause it to soften.

Although a heat plasticizable material as used in the present invention falls into the broad category of a thermoplastic material, it is to be distinguished from thermosetting and thermoplastic material generally. A heat plasticizable material is one which, in its applied state, is a solid. That is, for example, upon being placed upon the metal drive member as above described in a liquid form and then cured the material is a solid and the metal drive member can be bonded to an abrasive element by applying the solid coating directly thereto or to another coating of the material on the element. Alternatively the heat plasticizable material could be formed in sheets of solid material and cut to size and applied between the finishing element and the drive member. Additionally, the heat plasticizable material must become fluid or plastic upon the application of heat thereto and a solid again when the heat is removed so as to bond the metal drive member to the abrasive element.

Although a specific metal drive member has been disclosed with respect to the presently preferred embodiment of the present invention, it should be expressly understood that any metallic drive member which is desired may be utilized without departing from the scope or spirit of the present invention.

The metallic drive member as above described, is particularly adapted to function in accordance with the support member therefor in accordance with the present invention.

The Support Member Referring now more specifically to FIGS. 7 and 8, a support member in accordance with the present invention is provided for use in combination with the abrasive finishing article as above described. As is illustrated in FIG. 7, the abrasive article support member or support pad consists of a molded body portion 41 having a spindle 42 protruding therefrom for use in combination with a power driving tool. Disposed in a recess 43 in the under surface of the molded body portion 41 is a locking member 44 having a plurality of tabs 45, 46 and 47. The tabs 45 through 47 are utilized to cooperate with the openings 34, 34a and 34b in the metal drive member. The particular relationship between the tabs and the openings in the metal drive member will be more fully described hereinafter.

Referring now more specifically to FIG. 8, the particular detail construction of a support member in accordance with the present invention is illustrated. As is therein shown, there is provided a centrally disposed cylinder 51 having a bore 52 therein. The bore 52 is threaded as is illustrated at 53 to receive the threaded end portion 54 of a spindle 42. The spindle 42 has an enlarged portion such as a shoulder 55 thereon which mates with the upper portion of the cylinder 51. The shoulder 55 insures axial alignment of the spindle 42 with the center of the support member. The locking member 44 is centrally disposed within the recess 43 in the bottom surface of the molded body portion 41 of the support member. The locking member may be constructed in any manner which is desired, but preferably in accordance with the present invention, it is constructed of a pair of metallic plates 56 and 57. The plate 56 has the tabs 45 through 47 struck therefrom as by stamping, or the like. The locking member 44 is fitted upon the cylinder 51 by means of a drive screw 58 which is forced into an opening in the closed end of the cylinder 51.

In the presently preferred embodiment of the present invention, the two plates 56 and 57 comprising the locking member 44 are copper coated to a degree sufiicient to permit the entire sub-assembly to be furnace brazed.

Brazing paste is applied about the periphery of the cylinder 51 adjacent the plate 57 to cause the plates 56-57 and cylinder 51 to adhere together and become an integral rigid member.

Slipped about the outer portion of the cylinder 51, but in a non-attached fashion, is an annular metallic washerlike member 59. This entire sub-assembly is placed within a mold along with a layer 60 of fabric, such as neoprene impregnated cloth. The fabric 6% forms the bottom surface of the support member for the abrasive finishing article in accordance with the present invention. The mold is then filled with the particular desired compound such as neoprene to form a body portion 41 as illustrated in FIGS. 7 and 8. Upon cooling and removal from the mold, the completed support member for the abrasive finishing article in accordance with the present invention is provided.

As will become readily apparent to those skilled in the art, the internally threaded cylinder 51 permits a ready means of changing drive spindles, such as that illustrated at 42, to fit any desired power tool which may be available at the point or site of utilization. For example, many of the power tools will require a one-quarter inch spindle, of the type such as illustrated in FIG. 8, while in some cases, a threaded spindle is required or in other cases an irregularly shaped spindle may be utilized.

Such a support member may then be utilized in conjunction with the abrasive finishing article as above described.

The Combination of the Abrasive Finshing Article and the Support Member By referring to FIGS. 9 and 10, the particular relationship of the tabs which form a portion of the support member in accordance with the present invention and the openings which are formed in the drive member as above described, are illustrated and will be described in detail. For purpose of clarity of illustration and description, only a top fragmentary elevational view of the metal drive member and finishing article in accordance with the present invention and the tabs which are used in conjunction therewith and shown removed from the support member are illustrated. In FIG. 9 the tabs and the openings are shown in their unlocked relationship with the drive member. In FIG. 10 the openings and the tabs are illustrated in their locked relationship as when the abrasive finishing article is locked to the support member and is in a position to be utilized upon a workpiece.

The critical relationship in the unlocked position is that the openings each are sufiiciently large to permit the tabs on the drive member to readily and easily fall within the opening to facilitate attachment of the finishing article to the support member.

The critical relationship in the locked position is that the bearing surfaces of the openings and the tabs on the drive member be in a line-to-line contact, that is, a substantially interference fit. By providing such an interference fit between the bearing surfaces of the tabs and the openings, it is insured that the abrasive finishing article when attached to the support member therefor will not laterally oscillate across the surface of the support member irrespective of the speed of rotation or the power which is imparted thereto during application to the particular workpiece.

Referring now more particularly to FIG. 9 the specific relationship of the openings 34 and 34a and the tabs 45 and 46 is shown. The following detailed description will be given with respect to opening 34 and tab 45, it being understood that the remaining openings and tabs are identical. Opening 34 is provided with a first straight edge 35 and a second straight edge 36. The second straight edge 36 may also be viewed as the driving or bearing surface of the opening 34. The outermost ends of each of the two straight edges are interconnected by a surface 48 which becomes decreasingly smaller in radius when going from edge 35 to edge 36 and with reference to the center of the drive member 31. The innermost ends of the two straight edges are interconnected by a surface 49 which continuously increases in radius with similar reference points. In this manner there is provided an opening which easily and readily receives the tab in unlocked relationship. As can be seen the tab falls into the opening with adequate clearance on all sides. It should also become obvious that the edge 35 need not be a straight edge so long as proper clearance is provided for the tab and so long as the edge 36 is a straight edge for line-to-line engagement with surface 61 of the tab.

It should be particularly noted that the straight edge 36 is smaller than the straight edge 35. In this manner the straight edge 35 is made substantially the same length as the surface 61 of the tab 43. This relationship is more clearly illustrated in FIG. 10. This is a critical point of the present invention. By constructing the bearing surfaces of the tab and the opening of equal length the finishing article may be rotated at exceedingly high speeds with no lateral movement of the finishing article across the surface of the support member.

The line-to-line contact between the bearing surfaces of the tabs and openings is important from another aspect. As is well known in the finishing art it is important to apply as much power as possible to the finishing article without fracturing the drive member thereof. It is also important to maintain flexibility over as large an area of the finishing article as possible. Since the amount of power applied to the finishing article is limited only by the strength of the user and the capacity of the power tool, no control thereover during use can be exercised by the manufacturer. As a result prior art devices have been constructed with the locking and driving members occupying a relatively large area of the support member thus reducing flexibility.

The line-to-line bearing surfaces between the tabs and the openings, in accordance with the present invention, permit the locking and driving members to occupy a relatively small area of the support member and finishing article while at the same time permitting the application of maximum power thereto thus maintaining the desired flexibility.

An important feature of the present invention is illustrated in FIG. 11 which shows an abrasive finishing article in the position of being attached to a support member therefor and also in fully assembled position.

To attach an abrasive finishing article of the type above described to a support member therefor it is necessary to apply pressure at the center of the abrasive surface to force the openings in the drive member completely over the tabs on the locking member. This may be easily accomplished by bending the edges of the finishing article downwardly and at the same time pushing the center thereof upwardly. After thus fitting the tabs into the openings, the finishing article is rotated relative to the support member and is thereby firmly attached.

In the attached position (FIG. the finishing article is released as shown (FIG. 11). However, the inner surfaces of the tabs bear against the inner surface of the metal drive member in such a manner that tension is maintained upon the finishing article. This is particularly important for it causes the finishing article to be very firmly held in place at all times during use and thus prevents inertial fly off if the rotation of the finishing article is suddenly stopped and axial pull off even under severe operating conditions. As is well known, inertial fly off and axial pull off have been long felt and heretofore unsolved problems in the abrasive finishing art.

This positive locking feature of the present invention is accomplished in the following manner. The distance between the inner surface of the metal drive member and the top of the finishing article (shown at :12 in FIG. 6) is first predetermined for any given size of drive memher. The distance between the inner surface of the tabs and the surface of the support member (as shown at d1 in FIG. 11) is then predetermined. The distances 031 and d2 are predetermined such that d1 is always greater than d2 for any given finishing article and the support member therefor. As can, therefore, readily be seen, the face of the support member is constantly in effect, causing 1% the drive member to push outwardly against the tabs. This outward tension in turn tends to cause the tabs to bite into the plastic coating on the inner surface of the drive member to thereby more firmly retain the finishing article on the support member. To facilitate attachment of a finishing article in accordance with the present invention, the recess in the face of the support member is constructed to have a larger diameter than the drive member.

Another important feature of the present invention is that a heat conducting path is provided from the back surface of the abrasive finishing article by way of the metal drive member. Heat is further conducted through the locking member, cylinder and shaft into the power tool. Thus heat generated at the surface of the finishing article may be conducted therefrom more readily than similar rior art articles.

Particular note should be given to the respective diameters of the finishing article and the support member. It can be seen that the diameter of the finishing article is slightly larger than the diameter of the support member. This construction provides extreme flexibility at the periphery of the finishing article and permits a workman to use the finishing article in extremely small radius areas of a workpiece. The increase in diameter of the finishing article is just sufiicient to permit the finishing article to cover the edge of the support member and thereby to eliminate the drag or" the support member against the workpiece.

There has thus been disclosed finishing apparatus which is more eflicient and effective than similar prior art apparatus while solving problems existent in such prior art apparatus.

Although various features and concepts of the present invention have been set forth in the foregoing illustrative embodiment, the present invention is not to be limited in accordance therewith but is to be construed in accordance with the claims set forth below.

What is claimed is:

1. A finishing article and supporting member therefor, said article comprising: an imperforate layer of finishing material; a backing member permanently secured to said layer of finishing material; said backing member being at least one layer of fabric penetrated a first coating of heat plasticizable plastic material coextensive with one surface of said backing member; a metallic driving menu her; a second coating of heat plasticizable plastic material on said metallic driving member, said first and second coatings being fused together to permanently bond said driving member to said backing member; said driving member having a raised portion forming a cavity with said plastic coating, said raised portion defining a plurality of openings therein each having at least one straight edge; and a plurality of tabs extending from said support member for cooperable locking engagement with said openings, each of said tabs having a fiat drive surface of a length substantially the same as the length of said straight edge.

2. A finishing article comprising: an imperforate layer of finishing material; a backing member permanently secured to said layer of finishing material; a first coating of heat plasticizable plastic material coextensive with one surface of said backing member; a metallic driving member; a second coating of heat plasticizable plastic material on said metallic driving member, said first and second coatings being fused together to permanently bond said driving member to said backing member.

3. A finishing article in accordance with claim 2 in which said metallic driving member has a raised portion providing a cavity with the backing member, said raised portion defining a plurality of openings therein for engagement with a supporting member for said finishing article, the inner surface of said raised portion facing said backing member having a coating of heat plasticizable material thereon.

4. A finishing article in accordance with claim 2 in 1 1' which said backing member includes at least one layer of fabric.

5. A finishing article in accordance with claim 4 which includes a layer of fibrous material permanently secured between said finishing material and said fabric layer.

6. The method of making an abrasive finishing article comprising: providing a sheet of abrasive finishing mate rial; coating a sheet of backing material on one surface thereof with a heat plasticizable plastic material; permanently affixing the other surface of said coated sheet of backing material to said sheet of abrasive finishing material to expose said plastic coating; coating one surface of a sheet of metal with a heat plasticizable plastic material; forming a metallic drive member from said coated sheet of material; contacting said plastic coating on said backing member with the coating on said metallic drive member; and applying heat only to that portion of said drive member in contact with said coating on said backing member for a predetermined period of time to fuse said plastic coatings and bond said drive member to said coating.

7. The method of making a finishing article comprising: providing a sheet of abrasive finishing material; applying a coating of polyvinyl chloride plastic material to one surface of a sheet of fabric and permitting said polyvinyl chloride to penetrate said fabric through a distance equal to less than the thickness thereof thereby to provide one uncoated surface and one permanently coated surface; permanently affixing said uncoated surface of said coated sheet of fabric to said sheet of abrasion finishing material to fully expose said plastic coating; coating one surface of a sheet of metal with a heat plasticizable plastic material; forming a metallic drive mem ber from said coated sheet of metal; contacting only a portion of said plastic coating on said fabric with said coating on said, metallic drive member; and applying heat to that portion of said drive member in contact with said coating on said fabric for a predetermined period of time to fuse said plastic coatings and bond said drive member so said fabric coating.

8. The method of claim 7 including the further step of permanently afiiXing a layer of fibrous material between said sheet of finishing material and said sheet of coated fabric.

9. A finishing article comprising: a layer of finishing material; a backing member permanently secured to said layer of finishing material; a first coating of heat plasticizable plastic material coextensive with one surface of said backing member; a metallic driving; and a second coating of heat plasticizable plastic material on one surface of said driving member, said first and second coatings being fused to permanently bond said driving member to said backing member, said metallic driving member having a raised surface portion defining a plurality of openings therein, each of said openings having first and second straight edges, said first straight edge being longer than said second straight edge, a first curved surface having a continuously decreasing radius interconnecting the outer ends of said straight edges, and a second curved surface having a continuously increasing radius interconnecting the inner ends of said straight edges.

10. A finishing article for use in combination with a support member therefore, said finishing article comprising; an impregnate layer of finishing material; a backing member permanently secure to said layer of finishing material; said backing member being at least one layer of fabric coated on one surface thereof with a heat plasticizable plastic material; and a metallic driving member coated on one surface thereof with a heat plasticizable plastic material, said coatings being fused to permanently bond said driving member to said backing member, the

diameterof said driving member being substantially less than the diameter of said finishing material.

11. A finishing article comprising: an imperfora-te layer of abrasive finishing material having a backing member permanently secured thereto; a first coating of heat plasticizable plastic material covering that surface of said backing member opposite said abrasive; a metallic drive member having a centrally raised planar portion and a lower portion, said raised portion defining a plurality of openings therein for engagement with a supporting member for said finishing article; a second coating of a heat plasticizable plastic material on the lower portion of said metallic drive member, said coatings of plastic material being fused together only over the area of said lower portion of said drive member to permanently bond said metallic drive member to said backing member.

12. An abrasive finishing article comprising: a backing member having first and second sides; an imperforate layer of abrasive finishing material permanently secured to said first side of said backing member; a coating of heat plasticizable plastic material covering at least a portion of said second side; a metallic drive member having a coating of heat plasticable plastic material on at least a portion of one surface thereof, said coatings of plastic material being fused together over at least a part of their respective areas thereby to permanently bond said drive member to said backing member.

13. An abrasive finishing article comprising: a backing member having an imperforate layer of abrasive permanently afiixed to one side thereof; a metallic drive member permanently afiixed to the other side of said backing member; and a layer of heat plasticizable plastic material between said drive member and said backing member, said heat plasticizable plastic material being the sole means to permanently bond said drive member to said backing member.

14. An abrasive finishing article comprising: an imperforate abrasive finishing element; a metallic drive member including means for engagement with a supporting member for said article; and a layer of heat plasticisable material sandwiched between said finishing element and said drive member and permanently bonding them together.

15. An abrasive finishing article comprising: an imperforate abrasive finishing element; a metallic drive member including a flange and a raised portion defining a plurality of openings therein for engagement with a supporting member for said article; and a layer of heat plasticizable material sandwiched between said finishing element and the flange on said drive member and permanently bonding said drive member and said finishing element together.

References Cited in the file of this patent UNITED STATES PATENTS 2,520,763 Goepfert et al Aug. 29, 1950 2,701,191 Laliberte Feb. 1, 1955 2,701,192 Maass Feb. 1, 1955 2,747,343 Gellert May 29, 1956 2,781,618 Larson Feb. 19, 1957 2,839,879 Eisenbeis June 24, 1958 2,937,934 Nefilen May 24, 1960 2,943,926 Goepfert July 5, 1960 2,965,464 Rupprecht Dec. 20, 1960 2,996,851 Gianat-asio Aug. 22, 1961 3,014,795 Schmidlin Dec. 26, 1961 FOREIGN PATENTS 118,147 Australia Mar. 2, 1944 849,970 Germany Sept. 18, 1952 

13. AN ABRASIVE FINISHING ARTICLE COMPRISING: A BACKING MEMBER HAVING AN IMPERFORATE LAYER OF ABRASIVE PERMANENTLY AFFIXED TO ONE SIDE THEREOF; A METALLIC DRIVE MEMBER PERMANENTLY AFFIXED TO THE OTHER SIDE OF SAID BACKING MEMBER; AND A LAYER OF HEAT PLASTICIZABLE PLASTIC MATERIAL BETWEEN AND DRIVE MEMBER AND SAID BACKING MEMBER, SAID HEAT PLASTICIZABLE PLASTIC MATERIAL BEING THE SOLE MEANS TO PERMANENTLY BOND SAID DRIVE MEMBER TO SAID BACKING MEMBER. 